Reusable container closure cap

ABSTRACT

A closure cap particularly suited for use with containers such as milk bottles includes multiple sealing areas as well as frangible locking means. The locking means is located near the lower rim of a skirt portion of the closure cap. If the locking means has not been tampered with, an interlocking engagement between the locking means and a complementary portion of the container retains the cap on the container. If the locking means has been tampered with, the cap can be removed from the container. A visual inspection of the closure cap readily indicates whether the locking means is in tampered or untampered condition. In one embodiment, the cap can be repeatedly snapped into place on the container, and in other alternative embodiments, the cap can be repeatedly threaded onto the container. The multiple sealing areas not only seal the contents of the container, but one of the areas also prevents dust, dirt, or other contaminants from having access to the other sealing areas.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to closure caps for containers and, moreparticularly, to a reusable closure cap for containers having multiplesealing zones aand a frangible locking means which can visually indicatewhether the container has been opened.

2. Description of the Prior Art

Closure caps having a tamperproof feature have become an important itemof commerce. Generally speaking, closure caps of this class include alocking member of some kind which interacts with a locking memberincluded as part of a container. Upon breaking the closure cap lockingmember, the cap can be removed from the container. Desirably, theclosure cap locking member can be inspected visually to determinewhether it has been tampered with. Accordingly, a consumer can readilydetect whether the container has been opened previously. Althoughcontainer closures of this general class can function effectively,certain problems have not been addressed. One of these problems relatesto reusability of the closure cap. With many closure caps made of aplastics material or metal foil, a so-called tear tab is pulled when itis desired to remove the closure cap from the container. Rupture zonesoften are provided in order to permit the tab to be torn easily.Sometimes the tab tears completely through the side wall of the cap andinto the top wall of the cap. When this occurs, either by design or byaccident, it is easy to remove the cap from the container, but the capcannot be reused to seal the container again.

In an attempt to avoid the foregoing problem, container closure capshaving tear tabs which do not enter the top wall of the cap have beenprovided. Certain of these caps are not reusable because, during theopening process, a skirt portion of the cap is sufficiently weakenedthat a good sealing function no longer can be carried out. Other capsare known in which a small locking member in the skirt portion of thecap is broken, either to permit removal of the cap or upon removal ofthe cap, but these caps also suffer certain drawbacks with respect tosealing capabilities.

Particularly when sealing a container containing a substance such asmilk, it is quite important that the sanitary condition of the milk bemaintained. In addition to at least one primary sealing area, it isdesirable to provide a so-called bug shield in order to prevent dust,dirt, small insects, and so forth from having access even to the primarysealing area. Known container closures for milk containers either do nothave a bug shield or are expensive to manufacture. Desirably, a closurecap for a milk container would be inexpensive to manufacture, easy todetect whether it had been opened previously, would adequately shieldthe primary sealing area from contamination, and would have desirablequalties of appearance.

Other types of containers are best sealed by a threaded closure cap.Prior threaded closure caps having tear tabs have not performedparticularly well and tear tabs generally have been avoided withthreaded caps. One known threaded closure cap not employing a tear tabis usable repeatedly, but it is made of relatively thick metal and it isdifficult to initially untwist the cap from the container. In anotherknown closure cap made of a plastics material, a so-called tear ring isdisposed about the lower periphery of the cap. The tear ring includesserrations which engage mating serrations formed on the outer surface ofthe container. When it is desired to remove the cap, the tear ring isripped from the cap and thrown away. Thereafter, the cap can beunthreaded because the mating serrations no longer prevent removal ofthe cap.

A problem with the foregoing construction is that it sometimes isdifficult to grasp the tear ring in order to expeditiously remove it.Moreover, it is difficult to manufacture the cap such that the tear ringis connected to the remainder of the cap with material of the properthickness. That is, a circumferential line of weakness between the tearring and the remainder of the cap must be provided, and it is difficultto form such a line of weakness in a molding operation without rippingthe tear ring from the closure cap upon removal of the cap from themold.

SUMMARY OF THE INVENTION

The present invention overcomes the foregoing and other drawbacks inprior art proposals providing a novel and improved container closuresuitable for use with containers such as milk bottles. The containerclosure includes multiple sealing zones as well as frangible lockingmeans. The locking means, in untampered condition, locks the cap ontothe container and, in tampered condition, permits the cap to be removedfrom the container. The locking means can be readily inspected byobservation to determine if the container has been opened previously.

The closure cap includes a disc-like top wall from which an annularskirt depends. The top wall provides a primary sealing area for thecontainer. The skirt includes, on its inner surface, a first wallportion conforming generally to the outer contour of a first wallportion of the container. The skirt also includes a locking memberengageable with a locking member included as part of the container, aswell as a second wall portion. In one embodiment of the invention, thesecond wall portion of the closure cap seals against a shoulder portionof the container to prevent dirt or other contaminants from havingaccess to the primary sealing area. In this embodiment of the invention,the locking member also performs a sealing function.

In another embodiment of the invention, the first wall portion of theskirt includes threads which mate with complementary threads formed onthe container. A locking member included as part of the closure capengages a locking member on the container. In this embodiment of theinvention, the locking member of the closure cap is part of the secondwall portion of the cap. In yet another "threaded" embodiment of theinvention, the locking member is serrated and is engageable withserrations formed on the outer surface of the container.

In each embodiment of the invention, spaced, vertically extendingrupture zones extend from the lower rim of the skirt toward the top wallof the cap. The rupture zones do not extend into the top wall. Aflexible tab extends laterally outwardly of the skirt from a locationnear the lower rim of the skirt. Upon flexure of the tab, the rupturezones will fail, thereby permitting the skirt to expandcircumferentially near the lower rim of the skirt. In turn, the lockingmembers will be disengaged, thus permitting the cap to be removed fromthe container.

In the first-mentioned embodiment of the invention, the cap can bereused repeatedly simply by snapping the cap onto the container. In thisembodiment the second wall portion of the cap provides an effective "bugshield" prior to initial opening of the container. In the second andthird-mentioned embodiments, the threaded portion of the cap permits thecap to tightly seal the container, and yet the flexible tab does notinterfere with that function, even after the cap has been opened. Allembodiments of the invention can be formed expeditiously in a moldingoperation, and the particular construction and arrangement of elementsminimizes tolerances required during the molding operation.

The foregoing and other features and advantages, and a fullerunderstanding of the invention, may be had by referring to the followingdescription and claims, taken in conjunction with the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side elevational view of one embodiment of the inventionespecially adapted for use with milk containers;

FIG. 2 is a plan view of the container closure of FIG. 1;

FIG. 3 is a view taken along a plane indicated by line 3--3 in FIG. 2,with portions of the container broken away and removed for clarity;

FIG. 4 is a side elevational view of an alternative embodiment of theinvention, with a portion of a cap and container being shown incross-section;

FIG. 5 is a plan view of the container closure of FIG. 4 with a portionof the cap being shown in cross-section;

FIG. 6 is a view taken along a plane indicated by line 6--6 in FIG. 5;

FIG. 7 is a side elevational view of an alternative embodiment of theinvention, with a portion of a cap and container being shown incross-section;

FIG. 8 is a plan view of the container closure of FIG. 7; and

FIG. 9 is a view taken along a plane indicated by line 9--9 in FIG. 8.

DESCRIPTION OF THE PREFERRED EMBODIMENT

As used herein, such terms as "vertically," "downwardly," "upper" andthe like are intended to indicate the relative position of certainelements of the invention with respect to each other and no particularspatial orientation of the invention is required or is to be presumedfrom the use of these terms. Referring to FIGS. 1-3, a container closurecap according to the invention is indicated generally by the numeral 10.The closure cap 10 is formed in a molding operation from a plasticsmaterial such as high density polyethylene. The cap 10 is shown insealing position atop a container 20. The container 20 is in the form ofa typical milk bottle having a large body portion 22 and a generallycylindrical neck portion 24 having a tapered shoulder portion 26. Thecontainer 20 typically is formed in a blow-molding operation from asuitable plastics material.

The neck portion 24 includes an annular rim 28 having a generally flatupper surface. The neck portion 24 includes a cylindrical inner surface30 extending the length of the neck portion 24. The neck portion 24 alsoincludes a first wall portion 32 immediately adjacent the rim 28. Thefirst wall portion 32 is smooth-sided and cylindrical. A first lockingmember 34 is positioned vertically adjacent the first wall portion 32 onthe outer surface of the neck portion 24. The first locking member 34 isin the form of a cylindrical groove having a diameter smaller than thatof the first wall portion 32. A second wall portion 36 is locatedvertically adjacent the first locking member 34 and provides atransition between the neck portion 24 and the shoulder portion 26. Thesecond wall portion 36, like the first wall portion 32, is cylindricaland smooth-sided. The second wall portion 36 is approximately the samediameter as the first wall portion 32.

The closure cap 10 includes a disc-like top wall 40 having a centersection 42 slightly smaller in diameter than the inner diameter of theneck portion 24. A ledge 44 extends upwardly from the outer edge of thecenter section 42, and a rim 46, beveled on its outer surface, extendsfrom the periphery of the center section 42 in a direction opposite tothat of the ledge 44. A flange 48 extends laterally outwardly from theledge 44 and overlies the rim 28.

An annular skirt 50 depends from the top wall 40. The skirt 50 extendsdownwardly from the outer periphery of the flange 48. The skirt 50includes, on its inner surface, a third wall portion 52. The third wallportion 52 is smooth-sided and conforms generally to the contour of thefirst wall portion 32. A second locking member 54 is located verticallyadjacent the third wall portion 52. The second locking member 54 is inthe form of an inwardly projecting rim engageable with the first lockingmember 34. A fourth wall portion 56 is located vertically adjacent thesecond locking member 54 and extends to a lower rim 58 of the skirt 50.The fourth wall portion 56 is smooth-sided and conforms generally to thecontour of the second wall portion 36. The lower rim 58 is flaredoutwardly on its inner surface as at 60. When the closure cap 10 is insealing position atop the container 20, the inner surface 60 is insurface-to-surface contact with the shoulder portion 26.

The closure cap 10 also includes a flexible tab 70 extending laterallyoutwardly from the lower rim 58. A pair of spaced, vertically extendingrupture zones, or lines 72 extend from the lower rim 58 to a pointintermediate the lower rim 58 and the top wall 40. The rupture lines 72are connected at their upper end by a hinge line 74. The lines 72, 74essentially are areas of reduced material thickness (approximately 0.008inch). As can be seen in FIGS. 2 and 3, a wall section 76 is bounded bythe lines 72, 74 and is located slightly laterally outwardly of theouter diameter of the fourth wall portion 56. The tab 70 is an extensionof the lower portion of the wall section 76. Upon upward flexure of thetab 70, the rupture zones 72 will fail and the wall section 76 will bepivoted about the hinge line 74.

During initial assembly of the closure cap 10 atop the container 20, thecap 10 is placed atop the neck portion 26 and a compressive force isapplied uniformly to the flange 48. After enough force has been applied,the second locking member 54 will be slightly expanded, and the firstwall portion 32 either will remain dimensionally stable or will bereduced in diameter slightly. Although an interference fit is created,the relative dimensions of the cap 10 and the neck portion 24 are suchthat the cap 10 will be able to be moved axially into that positionshown in FIGS. 1-3. After the cap 10 is in that position illustrated inthe FIGURES, the container 20 will be sealed. Several sealing areas areprovided:

1. The interface between the upper, inner portion of the neck portion 24and the rim 46.

2. The interface between the upper surface of the rim 28 and theunderside of the flange 48.

3. The interface between the first wall portion 32 and the third wallportion 52.

4. The engagement between the first and second locking members 34, 54.

5. The interface between the shoulder portion 26 and the inner surface60 of the lower rim 58.

The first three sealing areas may be referred to collectively as aprimary seal. The fourth sealing area may be referred to as a secondaryseal. The fifth sealing area has been referred to previously and may beidentified as a tertiary seal. The surface-to-surface contact betweenthe shoulder portion 26 and the inner surface 60 effectively functionsas a "bug seal" to prevent dirt, dust, and other contaminants fromreaching the other sealing areas.

In order to remove the closure cap 10 from the container 20, the tab 70is lifted upwardly until the rupture zones 72 fail. At that point, thehoop strength in the lower portion of the skirt 50 is released. Underthese circumstances, axial force can be applied to the cap 10 and,because the lower portion of the skirt 50 now can be expandedcircumferentially, the first and second locking members 34, 54 can bedisengaged relatively easily. In turn, the cap 10 can be removed fromthe container 20. After the rupture zones 72 have failed, the cap 10 canbe removed and replaced as often as desired without adversely affectingthe primary and secondary sealing areas. Because the tab 70 and the wallsection 76 are readily observable by a consumer, it will be immediatelyapparent whether the cap 10 has been tampered with or removed from thecontainer 20. Unlike certain prior art closure caps, the closure cap 10according to the invention is relatively easy to open because the tab 70can be grasped without difficulty, and there is no need to dispose of asevered portion of the cap 10.

An alternative closure cap according to the invention is indicated inFIGS. 4-6 by the numeral 100. The cap 100 is suitable for use withcontainers having threaded neck portions. The cap 100 also can be usedfor sealing containers having relatively high internal pressures.

The cap 100 is illustrated in sealing position atop a container 120. Thecontainer 120 includes a relatively large body portion 22, and agenerally cylindrical, elongate neck portion 124 having a taperedshoulder portion 126. The neck portion 124 includes an annular rim 128having a rounded upper surface. The neck portion 124 includes acylindrical inner surface 130 extending the length of the neck portion124. The neck portion 124 also includes a first wall portion 132 havinga plurality of helical grooves 133 on its outer surface. The grooves 133function as a locking member. Another locking member 134 is positionedvertically adjacent the first wall portion 132 on the outer surface ofthe neck portion 124. The locking member 134 is in the form of anannular groove having a diameter smaller than that of the first wallportion 132.

The closure cap 100 includes a disc-like top wall 140. An annular skirt142 depends from the top wall 140. The skirt 142 extends downwardly fromthe outer periphery of the top wall 140 and terminates in a beveledlower rim 144. The skirt 142 includes, on its inner surface, a secondwall portion 146. The second wall portion 146 includes a plurality ofthreads 148 which interlock with the grooves 133 on the first wallportion 132 and thereby function as another locking member.

An additional locking member 150 is located near the lower rim 144 ofthe skirt 142. In effect, the locking member 150 is part of the secondwall portion 146. The locking member 150 is in the form of an inwardlyextending projection, or tooth, engageable with the first locking member134. The tooth 150 includes a flat upper surface 152 and a sharp inneredge 154.

An inwardly extending, flexible annular lip 156 is positioned at theinterface between the top wall 140 and the skirt 142. In use, uponapplying the cap 100 to the container 120, the lip 156 engages the rim128 to effect a fluid-tight seal. The engagement between the lip 156 andthe rim 128 may be referred to as a primary seal. The interlockinggrooves and threads 133, 148 of the wall portions 132, 146 create asecondary seal. The rim 144 and the shoulder 126 engage each other insubstantial surface-to-surface contact to create a tertiary seal.

The closure cap 100 also includes a flexible tab 160 extending laterallyoutwardly from the lower rim 144. A pair of spaced, vertically extendingrupture zones, or lines 162 extend from the lower rim 144 to a pointnear the top wall 140. The rupture lines 162 are connected at theirupper end by a hinge line 164. The lines 162, 164 essentially are areasof reduced material thickness (approximately 0.008 inch). As can be seenin FIGS. 5 and 6, a wall section 166 is bounded by the lines 152, 164and constitutes a continuation of the outer diameter of the skirt 142.Upon upward flexure of the tab 160, the rupture lines 162 will fail andthe wall section 166 will be pivoted about the hinge line 164.

During initial attachment of the closure cap 100 to the container 120,the cap 100 is placed atop the neck portion 124 and is threaded onto theneck portion 124. As the cap 100 is threaded, the tooth 150 will engagethe grooves 133 of the wall portion 132. The skirt 142 will be expandedslightly out-of-round, and the first wall portion 132 either will bedimensionally stable or will be reduced in diameter slightly. Althoughan interference fit is created, the relative dimensions of the cap 100and the neck portion 124 are such that the cap 100 be able to be movedaxially to that position shown in FIGS. 4-6. After the cap 100 is inthat position illustrated in the FIGURES, the container 120 will besealed and the cap 100 cannot be removed because of the engagement ofthe flat upper surface 152 with the groove 134.

In order to remove the closure cap 100 from the container 120, the tab160 is lifted upwardly until the rupture zones 162 fail. At that point,the hoop strength in the lower portion of the skirt 142 is released.Also, because the tooth 150 no longer engages the groove 134, a lockingfunction no longer is carried out by the tooth 150 and the groove 134.Accordingly, the cap 100 can be unthreaded from the container 120.Because the wall section 166 constitutes only a small circumferentialportion of the skirt 142, the skirt will not be expanded excessivelyupon re-tightening the cap 100 so as to disengage the grooves 133 andthe threads 148. Furthermore, the cap 100 can be removed and replaced asoften as desired without adversely affecting the seal created by the lip156 and the rim 128. Because the tab 160 and the wall section 166 can bereadily observed by a consumer, it will be immediately apparent whetherthe cap 100 has been tampered with or removed from the container 120.Moreover, the closure cap 100 according to the invention is relativelyeasy to open because the tab 160 can be grasped without difficulty, andthere is no need to dispose of a severed portion of the cap 100.

A third alternative closure cap according to the invention is indicatedin FIGS. 7-9 by the numeral 200. The cap 200, like the cap 100, issuitable for use with containers having threaded neck portions. The cap100 also can be used for sealing containers having relatively highinternal pressures.

The cap 200 is illustrated in sealing position atop a container 220. Thecontainer 220 includes a relatively large body portion 222, and agenerally cylindrical, elongate neck portion 224 having annular ledgeportions 226, 227. The neck portion 224 includes an annular rim 228having a flattened upper surface. The neck portion 224 includes acylindrical inner surface 230 extending the length of the neck portion224. The neck portion 224 also includes a first wall portion 232 havinga plurality of helical threads 233 on its outer surface. The threads 233function as a locking member. Another locking member 234 is positionedvertically adjacent the first wall portion 232 on the outer surface ofthe neck portion 224. The locking member 234 is in the form ofserrations spaced circumferentially of the neck portion 224. Theserrations 234 do not extend completely about the circumference of theneck portion 224, but are located at pre-determined circumferentiallocations where a locking function needs to be carried out. Thosecircumferential locations not including serrations 234 are occupied byvertically extending walls 236. As seen in FIG. 7, the walls 236 connectthe ledges 226, 227.

The closure cap 200 includes a disc-like top wall 240 having a centersection 242 slightly smaller in diameter than the inner diameter of theneck portion 224. A ledge 244 extends upwardly from the outer edge ofthe center section 42, and a rim 246, beveled on its outer surface,extends from the periphery of the center section 242 in a directionopposite to that of the ledge 244. A flange 248 extends laterallyoutwardly from the ledge 244 and overlies the rim 228.

An annular skirt 252 depends from the top wall 240. The skirt 252extends downwardly from the outer periphery of the top wall 240 andincludes a laterally extending ledge 254 from which a wall 256 extendsdownwardly. A rim 258, beveled on its outer surface, extends downwardlyfrom the skirt 252 at the inner periphery of the skirt 252. The skirt252 includes, on its inner surface, a second wall portion 260. Thesecond wall portion 260 includes a plurality of grooves 262 whichinterlock with the threads 233 on the first wall portion 232 and therebyfunction as another locking member.

An additional locking member 264 is included as part of the skirt 252.The locking member 264 is in the form of inwardly extending flexibleserrations engageable with the first locking member 234. The serrations264 project from the back face of a wall portion 266 having a diameterslightly larger than the diameter of the wall 256. The wall portion 266,as shown in FIG. 7, has a greater height than does the wall 256. Thewall portion 266 is connected to the skirt 252 by a ledge 268 and byvertically and horizontally extending rupture zones, or lines 270. Thelines 270 essentially are areas of reduced material thickness(approximately 0.008 inch). The ledge 268 includes an opening 272 toenable the serrations 264 to be formed expeditiously in a moldingoperation. A tab 274 extends outwardly from the lower portion of thewall 266. Upon upward flexure of the tab 274, the rupture lines 270 willfail and the wall section 266 will be pivoted upwardly.

During initial attachment of the closure cap 200 to the container 220,the cap 200 is placed atop the neck portion 224 and is threaded onto theneck portion 224. As the cap 200 is threaded, the rim 246 eventuallyengages the rim 228 to effect a fluid-tight seal. The engagement betweenthe rim 246 and the rim 228 may be referred to as a primary seal. Theinterlocking threads and grooves 233, 262 of the wall portions 232, 260create a secondary seal. The rim 258 and the ledge 266 engage each otherin substantial line-to-line contact to create a tertiary seal. Thelowermost portion of the wall 256 also engages the ledge 227 insubstantial surface-to-surface contact to create yet a fourth seal.After the cap 200 is in that position illustrated in the figures, thecontainer 220 will be sealed and the cap 200 cannot be removed becauseof the engagement of the interlocking serrations 234, 264.

In order to remove the closure cap 200 from the container 220, the tab274 is lifted upwardly until the rupture zones 270 fail. At that point,the hoop strength in the wall 256 is released. Also, because theserrations 264 no longer engage the serrations 234, a locking functionno longer is carried out by the serrations 264, 234. Accordingly, thecap 200 can be unthreaded from the container 220. Because the wallportion 266 essentially is only a circumferential portion of the wall256 and not the remainder of the skirt 252, the skirt 252 will not beexpanded upon retightening the cap 200 so as to disengage the threads233 and the grooves 262. Furthermore, the cap 200 can be removed andreplaced as often as desired without adversely affecting the sealcreated by the rims 246, 228, and the rim 258 and the ledge 226. Becausethe tab 274 and the wall portion 266 can be readily observed by aconsumer, it will be immediately apparent whether the cap 200 has beentampered with or removed from the container 220. Moreover, the closurecap 200 according to the invention is relatively easy to open becausethe tab 274 can be grasped without difficulty, and there is no need todispose of a severed portion of the cap 200.

In addition to the advantages of the invention described previously, itwill be appreciated that each embodiment of the invention can be formedexpeditiously in a molding operation. In particular, unlike certainprior caps, the vertically extending rupture lines can be molded easilyto close tolerances and the cap according to the invention can beremoved quickly from a mold even while still in a softened condition. Inpart, this is because forces required to remove the cap from the moldare exerted in the direction of the rupture lines, rather than laterallyof the rupture lines.

Although the invention has been described with a certain degree ofparticularity, it will be understood that the present disclosure of thepreferred embodiment has been made only by way of example, and thatnumerous changes in the details of construction and the combination andarrangement of elements can be resorted to without departing from thetrue spirit and scope of the invention as hereinafter claimed. It isintended that the patent shall cover, by suitable expression in theappended claims, whatever features of patentable novelty exist in theinvention disclosed.

What is claimed is:
 1. A closure cap for sealing the neck portion of acontainer such as a milk bottle, the neck portion having an upstandingannular rim, a first outer wall portion depending therefrom, a firstouter locking surface spaced from the rim and located about theperiphery of the neck portion beneath said outer wall portion, the firstwall portion having a diameter different from the diameter of the firstlocking surface,the closure cap being formed of a material havinglimited flexibility and comprising: (a) a disc-like top wall engageablewith said rim to effect a substantially fluid-tight seal; (b) an annularskirt depending from said top wall, the skirt having on its innerperiphery:(i) a second wall portion conforming generally to the outercontour of said first wall portion; (ii) a second locking sufacedisposed beneath said second wall portion and engageable with the firstlocking surface when the cap is in a container-sealing position; and,therebeneath, (iii) a lower annular skirt area having spaced generallyvertically extending rupture zones therein, the rupture zones notextending upwardly into said second locking surface, (iv) said first andsecond locking surfaces including complementary interfittingcircumferential annular rib and groove elements, and, (c) a tabprojecting laterally outwardly of the skirt from a location near thelower edge of said skirt, the tab being disposed between said verticallyextending rupture zones whereby, upon upward flexure of the tab, therupture zones will fail and permit said lower skirt area to becircumferentially expanded, thereby permitting the first and secondlocking surfaces to be flexibly disengaged to permit ready removal ofthe cap from the container and wherein the integrity of said lockingsurfaces remains intact notwithstanding failure of the rupture zonestherebelow to permit ready replacement of the cap onto the container forresealing the same.
 2. The closure cap of claim 1, wherein the lowerinner periphery of the skirt is flared outwardly and, in use, engagesthe container at a shoulder portion of the container.
 3. The closure capof claim 2, wherein the engagement between the cap top wall and the rimof the container defines a first seal, the engagement between the firstand second locking surfaces defines a second seal, and the engagementbetween the inner surface of the flared skirt and the shoulder of thecontainer defines a third seal, the three seals serving not only to sealthe contents of the container, but the third seal also serving toprevent dirt or other contaminants from having access to the first andsecond seals.
 4. The closure cap of 1, 2 or 3 further including anarcuate hinge area interconnecting the upper ends of said rupture zoneswhereby upon flexure of said lift tab causing said rupture zones tofail, said tab pivots about said hinge.
 5. The closure cap of claim 4wherein said lower annular skirt area between said rupture zones isdisplaced slightly radially outwardly from the remainder of the lowerannular skirt area thereat.